91 speedometer

[intimidator4x4]

I have searched threads, and I am still confused. I have a 91 truck with the gauge cluster with the tach. I want to get it recalibrated to my tires and gears. I read how to do a 92 and read about the moon gauges for 91 and older. I also have been told that my set up is kind of the bastard child of the 91's. So please any info will be appreciated.
Thanks Tim

[long&low]

It will be calibrated like the 88-91s.
The 92 and up use the DRAC.

[1ugly88]

you need a recalibration kit. unfortunatly i don't know where to find one. try your local dealer.

[lowdown]

There might be some useful information here:

http://www.koolcartoons.com/lowdown/speedo/

lowdown

[intimidator4x4]

It will be calibrated like the 88-91s.
The 92 and up use the DRAC.
I was told it was the same as the 92's

[1ugly88]

if it's the same as a 92 then it should already have a DRAC in it. if it does, i think it's located on top of the ECM behind the glove box. here is a link on how to modify the DRAC to make it adjustable.....

http://www.fullsizechevy.com/forums/general-discussion/tech-articles/69806-update-94-gauges-w-tach.htm

[lowdown]

I was told it was the same as the 92's
91 was the first year for the needle gauges (the tach was available as an option). The early 91's had the moonies and the late 91's had the needle gauges, and they kept the wiring the same.

In 92 they changed over to the DRAC and the wiring is different.

When I done the change on my 88 I went to the chevy dealership and researched wiring diagrams.

lowdown

[intimidator4x4]

Thanks for your help

[lowdown]

no problem.

Seriously though, you should find all of the information you need in this link:
http://www.koolcartoons.com/lowdown/speedo/

If you need a hand with the tire size I will be glad to try and help out.

lowdown

[JohnO356]

You will need the calibration kit for the late '91 cluster. Unfortunately, GM no longer produces them, but try your local dealer. If he doesn't have one in stock he can check his computer to find a dealer who has one.

[Striker49]

You will need the calibration kit for the late '91 cluster. Unfortunately, GM no longer produces them, but try your local dealer. If he doesn't have one in stock he can check his computer to find a dealer who has one.

And you'll be lucky to get one at a good price, if the dealer will even let it go. I think when I got mine there were only a dozen or so dealers that had them in stock.

[JohnO356]

You're right, Striker. Several dealers wouldn't sell a year or so ago, but I found one in Arkansa who obviously didn't know what he had. I got the whole kit for $44.31, shipping included. Besides the calibration tool, the kit contained two of the chips which sell for over $25.00 each. Still good deals out there, LOL.

[Striker49]

To be perfectly honest, one of those kits wouldn't be hard to make.

The easiest thing I could think to do would hit up a load of junk yards, tear out the old harnesses from behind the cluster (most of the vehicles already have the cluster removed anyways) and rewire it the way the kit comes. Fabbing up a clip wouldnt be extremely hard either.

[dfm25c]

I had a question regarding the different tire sizes. I know that the speedometer is based off a percentage, and will give you false readings when tire sizes are changed from the stock factory sizes. If I were to put a larger tire on a truck my speedometer would say I am going slower than I actually am, does the odometer record less miles then? I think it does.